Aromatic aldehydes, acids and esters, particularly those substituted on the aromatic ring with ether groups, are important compounds in the perfume industry, and also serve as precursors for the manufacture of pharmaceuticals. Previous methods for preparing the foregoing aromatic aldehydes, acids and esters involved either methylating phenolic aldehydes or introducing an aldehyde group into a preformed aromatic ether.
In a series of papers, Bacon and S. C. Rennison [J. Chem. Soc., (C), 308, 213, 1978 (1969)] reported that aromatic halides when treated with sodium methoxide in the presence of cuprous salts, notably cuprous iodide, produced aromatic ethers. The authors further reported, see page 312, that aromatic bromides bearing phenolic and/or aldehydic groups gave poor yields, that is, 36-46% of the corresponding ethers in the reaction. By the present invention, it has now been unexpectedly found that aromatic ethers bearing aldehyde and/or phenol groups, as well as acid and ester groups, can be prepared in excellent yields, that is, 85-95%, by treating the corresponding aromatic bromides with, for example, sodium methoxide in dimethylformamide in the presence of cuprous chloride as catalyst.